Data server with hot replaceable processing unit modules

ABSTRACT

A data server having a plurality of hot replaceable processing unit modules. Each module includes a motherboard having plugged therein: a CPU; a main memory; an I/O adapter card, and an interconnect printed board, electrically connected to the motherboard. A backplane has a first connector adapted for coupling to a DC power supply. The interconnect printed circuit board has a DC to DC converter connected to a second connector adapted to mate with the first connector to enable the processing unit module to be hot plugged into, or removed from, the backplane. The backplane has formed thereon a strip transmission line adapted to provide an Ethernet bus for interconnecting a plurality of the modules. A cable management system for a cabinet used to house the module includes at least one vertically extending channel disposed in the cabinet and a fastener adapted to open and enable the a cable to be inserted into the channel and close to retain such cable within the channel. A chassis having a plurality of shelves for supporting electrical modules with a partitioning member adapted for removable insertion onto one of the shelves to accommodate modules with different widths. An I/O adapter card mounting plate, with captive hardware, adapted for securing an array of I/O adapted cards, and honey-combed I/O adapter card filler plate to a case. A method for booting operating system software into a main memory of a processing unit.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to data servers and moreparticularly to data servers adapted to move data between a network anda data storage system.

[0002] As is known in the art, data servers are used to move databetween a storage system, such as between a Symmetrix Integrated CachedDisk Array storage system and a network. The data server typicallyincludes a set AC powered processing unit modules each of which includesa central processing unit (CPU), input/output (I/O) adapter cards, and amain memory programmed to run a variety of software application programsfor subscribers to the network. These applications include file access,video access and/or network backup. In one such data server, a set offive, AC powered, personal computers (PCs) are packaged inside astandard 19 inch cabinet. The five PCs are connected together via atwisted pair cable to an Ethernet hub. A laptop PC is used as a controlstation for the other PCs. A keyboard/monitor multiplexer (mux) was usedto pass each PC's boot sequence with a single keyboard and monitor.

SUMMARY OF THE INVENTION

[0003] In accordance with one feature of the invention, a data server isprovided having a plurality of hot replaceable processing unit modules.Each one of the processing unit modules includes a CPU, main memory andI/O adapter card.

[0004] In a preferred embodiment of the invention, the data serverincludes a backplane having a first electrical connector adapted forcoupling to a DC power supply. Each one of the processing unit modulesis DC powered. The module includes a motherboard having plugged therein:the CPU; the main memory; and the I/O adapter card. The module includesan interconnect printed board, electrically connected to themotherboard. The interconnect printed circuit board has mounted to it asecond electrical connector and a DC to DC converter electricallyconnected to the second electrical connector. The second electricalconnector is adapted to mate with the first electrical connector toenable the processing unit module to be hot plugged into, or removedfrom, the backplane.

[0005] In accordance with another feature of the invention, a dataserver is provided having a cabinet with a plurality of slots, orcompartments therein. Each one of the slots has a backplane disposed atthe rear thereof. A plurality of hot replaceable, DC powered processingunit modules is provided. Each one of the modules is adapted to beinserted in, or removed from, a corresponding one of the slots as suchone of the processing unit modules is plugged into, or un-plugged fromthe backplane.

[0006] In accordance with another feature of the invention a printedcircuit board is provided with a pair of overlying strip conductorsforming a strip transmission line. The strip transmission line isconfigured with electrical characteristics of a coaxial transmissionline.

[0007] In a preferred embodiment of the invention, the AC impedance andDC resistance of the strip transmission line are selected to configurethe strip transmission line as an Ethernet coaxial transmission line.

[0008] In accordance with another feature of the invention, a printedcircuit backplane is provided having an electrical connector adapted tomate with, and electrically connect to, an electrical connector of adaughterboard. The backplane has a pair of overlying strip conductorsforming a strip transmission line. The strip transmission line isconfigured with electrical characteristics of a coaxial transmissionline. In a preferred embodiment of the invention, the AC impedance andDC resistance of the strip transmission line are selected to configurethe strip transmission line as an Ethernet coaxial transmission line.

[0009] In accordance with another feature of the invention, a backplaneis provided having a first electrical connector mounted thereto adaptedto have plugged therein a daughterboard. The daughterboard has a secondelectrical connector adapted to mate with, and electrically connect to,the first electrical connector. The backplane has a first stripconductor disposed on one a surface of a dielectric substrate thereofand a second strip conductor on an opposite surface of the dielectricsubstrate. The first and second strip conductors are in overlayingrelationship to provide a strip transmission line from a coaxialconnector mounted to the backplane to the first electrical connector.

[0010] In a preferred embodiment, the strip transmission line providesan Ethernet bus on the backplane.

[0011] In accordance with another feature of the invention, a cablemanagement system is provided for a cabinet adapted to house electricalcomponents. The cable management system includes at least onelongitudinally extending channel disposed in the cabinet. A fastener isprovided adapted to open and enable the a cable to be inserted into thechannel and close to retain such cable within the channel.

[0012] In a preferred embodiment, the channel includes a portion of aframe of the cabinet.

[0013] In accordance with still another feature of the invention, achassis is provided having a plurality of shelves for supportingelectrical modules. A partitioning member is provided having captive,manually operable hardware adapted for removable insertion onto one ofthe shelves. The shelf has a pair of slots adapted to receive a pair ofmodules when the partitioning member is fastened to the shelf. Suchshelf has a single slot adapted to receive one module with width greaterthan the width of one of the pair of modules when the partitioningmember is removed from the shelf. The partitioning members of one of theshelves may be removed from, or inserted onto, the shelf withoutinterrupting operation of the modules on the other shelves.

[0014] In accordance with yet another feature of the invention, a powermanagement system is provided. The system includes a cabinet havingstored therein: a battery; a plurality of redundant, independentlyreplaceable battery chargers. One of the pair of battery chargers may bereplaced if defective without effecting the operation of the other oneof the battery chargers in charging the battery.

[0015] In accordance with still another feature of the invention, an I/Oadapter card mounting plate is provided for securing an array of I/Oadapter cards to a case. Each one of the I/O adapter cards has mountedthereto a mounting bracket. A motherboard is disposed in the case and isadapted to have plugged therein the array of I/O adapter cards. Themounting plate has captive fastening hardware and is adapted to beplaced over the mounting bracket as a single piece. The captive hardwareis adapted to enable manual fastening of the mounting member to securethe mounting bracket between the mounting plate and the case after thearray of I/O adapter cards has been plugged into the motherboard.

[0016] In accordance with yet another feature of the invention, anadapter card filler plate is provided. The filler plate has a pluralityof holes formed therethrough to provide a honey-combed structure. If anI/O adapter card is not needed, an adapted card filler plate issubstituted for it. The filler plate is fastened to a mounting bracketby the mounting plate. The honey-combed, adapted card filler plateimproves air-flow through the case.

[0017] In accordance with still another feature of the invention, amethod is provided for booting operating system software into a mainmemory of a processing unit module. The method includes the step ofexecuting a program stored in the processing unit module to sequentiallysearch a plurality of possible sources of the operating system softwareduring a boot-up phase. When a possible source of the operating systemsoftware is detected, the CPU checks to determine whether such detectedsource is operational and has a valid boot format. If the detectedsource is operational and has a valid boot format, the CPU boots thedetected operating system software source into the main memory. If thedetected source is either non-operational or does not have a valid bootformat, the CPU checks another one of the possible operating systemsoftware sources. If all sources are checked and none are operationalnor have a valid boot format, the CPU repeats the aforementionedsequential search of the possible operating system software sources.

[0018] With such a method, the processing unit module is able tosuccessfully boot-up when the operating system software is stored in arelatively large memory system which may take a substantially long timeto be operational compared to the relatively short boot-up time of theprocessing unit.

BRIEF DESCRIPTION OF THE DRAWING

[0019] Other features of the invention, as well as the invention itself,will become more readily apparent from the following detaileddescription taken together with the accompanying drawings, in which:

[0020]FIG. 1 is a diagram of a data server according to the inventioncoupled between a memory system and a network;

[0021]FIG. 2 is a drawing of the data server of FIG. 1;

[0022] FIGS. 3A-3C are simplified, diagrammatical sketches of the dataserver of FIG. 1, FIG. 3A showing the front door of a cabinet used tostore the components of the data server of FIG. 2, FIG. 3B showing thefront of the cabinet when the front door of FIG. 3A is open; and FIG. 3Cis a rear view of the cabinet when a rear door thereof is open.

[0023]FIGS. 4A and 4B are perspective views of the data server of FIG.2; FIG. 4A being a rear perspective view of the data server with therear door open; and FIG. 4B being a front perspective view of the dataserver with the front door open; FIGS. 4C and 4D are front perspectiveand top diagrammatic drawings of the data server of FIG. 2 with thecabinet thereof being shown in phantom; and FIG. 4E is a rear view of aset of four backplanes used by the server of FIG. 2;

[0024] FIGS. 5A-5H are drawings of a processing unit module used aseither a data mover or control station in the data server of FIG. 2; anexemplary one of the data movers and control stations being shown inFIGS. 5A-5G; FIGS. 5A, 5B, 5G showing an exemplary one of the data movermodule; and FIGS. 5F and 5H show an exemplary one of the control stationmodules; FIGS. 5C and 5E are diagrammatical in nature and representeither a data mover or control station modules; FIG. 5D shows aprocessing unit module case prior to being configured as either a datamover or control station processing unit module;

[0025]FIG. 6 is a block diagram of a power management system, accordingto the invention, used in the server of FIG. 2;

[0026]FIG. 7 is a diagrammatical sketch showing a Ethernet striptransmission line, according to the invention, formed on a backplane andused to interconnect modules plugged into the backplane and coaxialcables used to interconnect a plurality of such backplanes;

[0027]FIG. 8 is a block diagram of the data server system of FIG. 1;

[0028]FIGS. 9A though 9D are drawings used to illustrate an I/O adaptercard mounting plate according to the invention; FIG. 9A is a sketch ofan array of such I/O adapter cards; FIG. 9B is an explodedcross-sectional diagrammatical sketch showing the arrangement betweenthe mounting plate, an I/O adapted card and a mounting member providedon a front bezel of a module; and FIG. 9C is an isometric, explodeddrawing of the I/O adapter plate mounting member according to theinvention;

[0029] FIGS. 9E-9G are drawings of an I/O adapter card filler plateaccording to the invention adapted for use in place of an I/O adaptercard in FIGS. 9A-9D, FIG. 9E being a perspective view of the fillerplate and FIGS. 9F and 9G showing the filler plate of FIG. 9E mounted tothe front bezel of a module;

[0030] FIGS. 10A-10F are drawing useful in understanding a the operationof a locking mechanism used by the modules; FIGS. 10A-10D showing thelocking mechanism in the locked position and FIGS. 10E and 10F showingthe locking mechanism in the unlocked position;

[0031] FIGS. 11A-11G are perspective views of a chassis used by theserver of FIG. 2 to store up to four processing unit modules shown inFIG. 5A; FIG. 11A showing the chassis with partitioning members; FIG.11B and 11C being perspective views of front and rear partitioningmembers, respectively, adapted for use with the chassis of FIG. 11A;FIG. 11D being a perspective, exploded view of the chassis with thepartitioning members of FIG. 11B and 11C; FIG. 11E is a sketch showingthe chassis of FIG. 11A with the partitioning members of FIGS. 11A and11B mounted therein to provide such chassis with four slots to receivefour modules as shown in FIG. 11F; and FIG. 11G is a rear perspectiveview of the cabinet of FIG. 11A;

[0032] FIGS. 12A-12D are drawings useful in understanding “blind mating”between a module of FIG. 5B and its mating backplane of FIG. 4C;

[0033]FIGS. 13A and 13B are drawings showing strip conductor circuitrydisposed on a front and rear surface of a dielectric substrate used inthe backplane of FIG. 4C, such strip conductors overlaying each other toform a strip transmission line Ethernet bus of FIG. 7;

[0034]FIG. 14A is a perspective view of the cabinet shown in FIG. 2,such view showing a cable management system according to the invention;FIG. 14B is an exploded view of a portion of the drawing in FIG. 11Asuch portion being inclosed by a circle labelled 14B-14B in FIG. 14A;and FIG. 14C is a top view of the cable management system;

[0035]FIG. 15 is a diagram of the server of FIG. 2 connected to a testnetwork during factory test; and

[0036]FIG. 16 is a flow diagram of a method, according to the invention,for booting an operating system software into a main memory of each ofthe processing unit modules used in data movers and control stations ofthe data server of FIG. 2 during either factory test, as in FIG. 15 orduring normal operation, as in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS General Overview

[0037] Referring now to FIG. 1, a data server 10 is shown coupledbetween a storage system 12 and a network 14. The storage system 12 ishere a Symmetrix 3500 Integrated Cache Disk Array system manufacturedand sold by EMC Corporation, Hopkington, Mass., assignee of the presentpatent application. The storage system 12 is coupled to the data server10 through a Fast Wide Differential (FWD) SCSI interconnect 16, asshown.

[0038] The data server 10 includes, in a single cabinet 18 shown inFIGS. 2, 3A-3E, a plurality of, here up to sixteen hot replaceableprocessing unit modules 28. Up to fourteen of the processing unitmodules 28 are data movers 20, here labelled 20 ₁-20 ₁₄ and up to two ofthe processing unit modules 28 are control stations 22 here labelled 22₁-22 ₂. The processing unit modules 28 are all interconnected through alocal bus, here an Ethernet bus 24 (FIG. 1). (Hot replaceable means thata component can be removed and/or replaced without an interruption tothe system's, here server's, operation.) It should also be noted thatthe modules 28 are configured so that no cables need to be physicallyremoved from the module 28 in order to remove it from the cabinet 18.

[0039] There are sixteen slots, or compartments (FIG. 3B) in the cabinet18 into which the processing unit modules 28 (i.e., data movers 20 ₁-20₁₄ or control stations 22 ₁, 22 ₂) can be slidably inserted or removed.The slots are arranged in longitudinally, here vertically, extendingpairs; the top seven pairs being configured to receive data movers 20₁-20 ₁₄, and the bottom pair being configured to receive the controlstations 22 ₁, 22 ₂. One of the slots in the bottom pair can beconfigured as a fifteenth data mover 20 or it may be configured as aredundant control station 22. The data movers and control stations 20₁-20 ₁₄, 22 ₁-22 ₂ are connected to the storage system 12 through theSCSI interconnect 16, as noted above, and to the network 14 thoughbi-directional busses 26, as shown in FIG. 1.

[0040] The control stations 22 ₁, 22 ₂ have different functionsdepending on the software application that is running on the data server10 for a subscriber to the network 14, for example. Each data mover 20₁-20 ₁₄ or control station 22 ₁, 22 ₂ is disposed within a sheet metalcase to provide an enclosure for the processing unit module 28, as shownin FIGS. 4A and 4B. An exemplary one of the data movers and controlstation processing unit modules 28 is shown in FIGS. 5A-5G. It is notedthat FIGS. 5A, 5B, 5G show an exemplary one of the data mover 20processing unit modules 28, here data mover 20, while FIGS. 5F and 5Hshow an exemplary one of the control station 22 processing unit modules28, here control station processing unit module 28. FIGS. 5C and 5E arediagrammatical in nature and represent either a data mover 20 or controlstation 22. FIG. 5D shows a processing unit module 28, here an emptycase, prior to being configured as either a data mover or controlstation. Each processing unit module 28 is DC powered, environmentallycontrolled processing unit module. The processing unit module 28includes a motherboard having plugged therein a CPU, main memory, andI/O adapter cards, to be described in detail hereinafter. Suffice it tosay here, however, is that the processing unit modules 28 are hotreplaceable into, or from, the server 10 via four backplanes 30 ₁-30 ₄(FIGS. 3C, 3D and 3E). More particularly, the processing unit modules 28for data movers 20 ₁-20 ₄ are hot replaceable via backplane 30 ₁; theprocessing unit modules 28 for data movers 20 ₅-20 ₈ are hot replaceablevia backplane 30 ₂; the processing unit modules 28 for data movers 20₉-20 ₁₀ are hot replaceable via backplane 30 ₃; and, the processing unitmodules 28 for data movers 20 ₁₁-20 ₁₄ and for control stations 22 ₁, 22₂ are hot replaceable via backplane 30 ₄.

[0041] Referring again also to FIG. 3B, the data server 10 also includesa CD ROM drive 50, accessible when the front door 36 of cabinet 18 isopened, and a multiplexer board (MUX) 53.

[0042] Referring to FIGS. 3A-3C, the data server 10 includes a flatpanel display 32 and keyboard with trackball mounted on the front door36 of the cabinet 18.

[0043] The data server 10 also includes a power management system 40, tobe described in more detail in connection with FIG. 6. Suffice it tosay, here, however that the data server 10 includes an Emergency PowerOff (EPO) box 42 (i.e., a circuit breaker, line filters, controller andswitches to enable switch over from primary AC main line 37 a power feedto auxiliary AC main line power feed 37 b), a plurality of powersupplies (e.g., AC to DC converters) 38, one thereof being provided forredundancy. The AC to DC converters 38 are modular, redundant, andindependently hot replaceable via a connector plate, not shown, mountedto an L-shaped printed circuit board 44 (FIGS. 3C and 6). In order toprotect against power failure a battery back up (BBU) unit 46 isprovided. The battery back up unit (BBU) 46, which includes battery 47,is charged by a pair of redundant battery chargers 48 a, 48 b eachindependently hot replaceable via the connector plate, not shown,mounted to the L-shaped printed circuit board 44, for charging thebattery 47.

[0044] Also provided are a pair of power control boards (COMMBDs) 52.The COMMBDs 52 will be described in more detail below in connection withFIG. 6 and the power management system 46. Suffice it to say here,however, that the COMMBDs 54 are coupled to the server backplanes 30₁-30 ₄ though the L-shaped printed circuit board 44, as shown in FIG. 6.Each COMMBD 54 is adapted to sense a variety of conditions, including:which data movers 20 ₁-20 ₁₄ are present in each data mover backplane 30₁-30 ₄; which backplanes 30 ₁-30 ₄ are present; whether there areEthernet bus 50 ohm terminator resistors 56, to be described in moredetail in FIG. 7 in connection with the internal Ethernet bus 34, aportion of which is formed as a strip transmission line 58 on thebackplanes 30 ₁-30 ₄; how many battery chargers 48 a, 48 b there are andwhether their cables are plugged in; whether the EPO 42 is present orabsent; the number of power supplies 38 (i.e., one to six); mux board 53present or absent; and, CDROM 50 present or absent.

[0045] The L-shaped printed circuit board 44 is the wiring backbone ofthe data server 10. There are two facets to the L-shaped printed circuitboard 44: there are connections on the L-shaped printed circuit boarditself to enable its connection to the backplanes 30 ₁-30 ₄ by a ribboncables 31; and, there is a connector plate, not shown, mounted to theL-shaped printed circuit board 44 for plugging in the EPO box 42 andbattery chargers 48 a, 48 b allowing for “quick-disconnect” of thebatteries chargers 48 a, 48 b.

Server 10 System Block Diagram

[0046] Referring now to FIG. 8, a system block diagram of the dataserver 10 is shown. As noted above, the processing unit modules 28(i.e., data movers 20 ₁-20 ₁₄ and control stations 22 ₁, 22 ₂)communicate with each other through an Ethernet bus 24, here a pair ofredundant Ethernet busses 24 a, 24 b, as shown, to the network 14 via anATM, Ethernet or FDDI bi-directional buses 26 (FIG. 1), for example, andto storage system 12 via the FWD SCSI, or Fibre channel interconnect 16(FIG. 1).

[0047] It is noted that the control stations 22 ₁, 22 ₂ each includes afloppy disk 60 and optional hard drive 62. The control stations 22 ₁, 22₂ are also here shown connected to the network 14 with ATM buses,however, it should be understood that other buses may be used such asEthernet or FDDI, for example. As noted above, here the control stations22 ₁, 22 ₂ are connected to the storage system 12 through SCSI channels16, here a pair of redundant SCSI channels. The control stations 22 ₁,22 ₂ are adapted for coupling to modems, not shown, via communication,or COMM ports 64, as indicated. The control station 22 ₁, 22 ₂motherboards 67, to be described in connection with FIGS. 5C, 5E, areprovided with keyboard, mouse, VGA and IDE interface cards 66 forenabling connection to a flat panel display 32, keyboard 34, mouse andCDROM drive 50 via multiplexer 53, as indicated. Thus, the controlstations 22 ₁, 22 ₂ have access thereto though the multiplexer 74.Therefore, the two control stations 22 ₁, 22 ₂ share a common display32, keyboard 34, mouse and CDROM 50. One of these control stations 22 ₁,22 ₂ can act as a redundant control station so that if one of the twocontrol stations 22 ₁, 22 ₂ fails, the other one is still operational.Likewise, if one of the pair of Ethernets 24 a, 24 b (FIG. 6) fails, thedata server 10 can operate with the other one. If one of the storagechannels, here FWD SCSI channels 16 a, 16 b, fails, the other one stillenables communication with the storage system 14. As noted above, thereis redundancy in AC-DC converters 38 and battery chargers 48 a, 48 b.

[0048] The control stations 22 ₁, 22 ₂ are responsible forcommunications interconnect between themselves and the data movers 20₁-20 ₁₄, via server interconnect printed circuit boards 68 in eachcontrol station 22 ₁, 22 ₂ and data mover 20 ₁-20 ₁₄. The systeminterfaces (e.g., environmental, internal Ethernet communications,modem, and network and storage) are all available to the controlstations 22 ₁-22 ₂. The particular functions of the control stations 22₁, 22 ₂ may vary depending upon the application in use, but generallyinclude: management of the individual data movers 20 ₁-20 ₁₄, powermanagement and cooling (i.e., environmental) management. The controlstations 22 ₁, 22 ₂ include, in addition to the motherboard 67 (FIG. 5E)with six I/O adapter card slots, a 3.5 inch high density floppy diskdrive 60, as shown in FIG. 5H.

[0049] The processing unit modules 28 are powered by AC-to-DCconverters, i.e. power supplies) 38 which are fed by the dual line ACthrough the EPO box 42 to the AC-to-DC converters 38. The output of theAC-to-DC converters is here 48 volts DC and is fed to each of the DC toDC converters 70 mounted to each of the server interconnect printedcircuit boards 68 (FIG. 5E) included within each one of the processingunit modules 28, described above. There is a battery backup unit (BBU)46. There are two redundant, hot replaceable, battery chargers 48 a, 48b (FIG. 6) external to the battery backup unit 46. AC power may be lostup to several minutes, during which time the battery 47 in the BBU 46will power the server 10. Charge is maintained in the BBU 46 by one ofthe two, independently hot replaceable battery chargers 48 a, 48 b. Itwas recognized that what typically fails in a system having a backupbattery 47 (FIG. 6) is the battery charger. Thus, here, the batterychargers 48 a, 48 b are external to the battery 47 and each of thechargers 48 a, 48 b, one being redundant, is hot replaceable, as shownin FIGS. 4A, 4B, 6. Thus, rather than embedding the chargers 48 a, 48 bin the BBU 46 and thereby having to replace an entire, relatively heavy,typically 50 pounds BBU 47 in the event of a battery charger failure,here the technician merely hot un-plugs the failed one of the twobattery chargers 48 a, 48 b and replaces it with an operational batterycharger while the server 10 continues to operate without interruption.When AC power is present from either the main AC line 37 a or theauxiliary AC line 37 b, the AC-DC converters 38 provide power to theprocessing unit modules 28 via a 48 volt bus system (i.e., a +48 voltbus and a ground bus) and one of the battery chargers 48 a, 48 bsupplies a trickle charge to the battery 47. It is noted that when thereis AC power present, the output voltage of the AC/DC converters 48 isslightly above 48 volts to back bias diode 72 a (FIG. 8) while diode 72b (one diode being included in each converter 48) is forward biased.When there is a complete failure of AC power, power to the processingunit modules 28 is supplied by the battery 47 via the 48 volt bus to thebackplanes 30 ₁-30 ₄. The one of the two battery chargers 48 a, 48 bproducing the highest potential is selected as the one to charge thebattery 47. As noted above, the data server 10 has n plus one AC-to-DCconverters 38 (i.e., power supplies 38); here, n is five.

[0050] Each processing unit module 28 includes an interconnect printedboard 68, electrically connected to (i.e., plugged into) the motherboard67. The interconnect printed circuit board 68 (i.e., a daughterboard forthe backplane 30) has mounted to it an electrical connector 93, to bedescribed, and a DC to DC converter 70 electrically connected to theelectrical connector 93. The electrical connector 93 of the interconnectprinted circuit board 68 is adapted to mate with, and electricallyconnects to, one of the backplane 30 ₁-30 ₄ electrical connectors 254 a,254 b, 254 c, or 254 d (FIG. 12B). DC power from the 48 volt bus systemis connected to pins of the backplane 30 ₁-30 ₄ connectors 254 a-254 d.The DC to DC converter 70 electrically connected to the electricalconnectors 254 a-254 d then distributes the 48 volts to other componentsof the processing unit module 28 and enables the processing unit module28 to be hot plugged into, or removed from, the backplane 30 ₁-30 ₄.

[0051] More particularly, each one of the processing unit modules 28includes a server interconnect printed circuit boards 68. As notedabove, each one of the boards 68 has mounted to it a DC-to-DC converter70. The DC to DC converter 70 creates the required DC voltages (i.e.,here +3.3, +5 volts, +12 volts, etc.) from a bulk 48 volt on the 48 voltbus that is distributed throughout the cabinet 18. More particularly,the 48 volts is then converted by the DC to DC converter 70 mounted tothe server interconnect printed circuit board 68 to the voltagesrequired by components, i.e., fans, CPU, optional disk drive, etc. inthe processing unit module 28. These required voltages may be, forexample, 5 volts DC, 12 or 3.3 volts DC. The server interconnect printedcircuit boards 68 each have mounted to them a pair of redundant Ethernettransceivers (XCVRs).

Data Mover/Control Station Processing Unit Module 28

[0052] As noted above, each data mover 20 ₁-20 ₁₄ or control station 22₁, 22 ₂ is disposed within a sheet metal case to provide a processingunit module 28, an exemplary one being shown in FIGS. 5A-5H. Each casehouses a DC powered, environmentally controlled processing unit module28. The processing unit module 28 includes the motherboard 67 (FIG. 5E)disposed on the bottom of the processing unit module 28, the data serverinterconnect printed circuit board 68 mounted along one side of theprocessing unit module 28, and a pair of DC fans 76, 78 disposed on theback of the processing unit module 28.

[0053] Referring also to FIGS. 5B and 5C, the server interconnectprinted circuit board 68 has mounted to it the DC to DC converter 70(FIG. 8), a DC margin and thermal control unit module, a pair of controlbusses, a pair of Ethernet 10 Base2 busses, a parallel port interfaceand various indicators 77 and switches 79 (FIGS. 5G and 5H) accessiblefrom the front panel of the processing unit module 28. The thermalcontrol unit processing unit module 28 is used to control the fans 76,78, and hence the environment, of such processing unit module 28. Theprocessing unit module 28 interconnect printed circuit board 68 (i.e., adaughterboard) plugs into the motherboard 67 (FIG. 5E). The DC fans 76,78 have a tachometer, not shown. and the server interconnect printedboard 68 has fan detection logic that determines if the fans 76, 78 arestill rotating properly. If a fan failure has occurred a fan_tach faultis presented to the control stations 22 via the backplane 30 ₁-30 ₄. Thecontrol stations 22 provide the mechanism in which to turn on/off thepower to an individual data mover/control station processing unit module28. Airflow through the data mover/control station processing unitmodule 28 is from front to back, as shown in FIG. 4B. The DC operatedfans 76, 78 pull air from slots in the front panel (FIG. 5B) of the datamover/control station processing unit module 28 and across themotherboard 67.

[0054] The motherboard 67 (FIG. 5E) has mounted to it a centralprocessing unit (CPU) 80, here a Pentium processor, a cache memory, mainmemory 82 a (FIG. 5C) (i.e., RAM SIMM modules adapted for insertion intoconventional SIMM slots 82), PCI bus slots 84, ISA bus slots 86. Theslots 84, 86 are adapted to receive plug-in standard I/O adapter cards,an exemplary array 85 being shown in FIG. 9A. (As will be described, thedata movers 20 ₁-20 ₁₄ here have four PCI slots 84, 86 and four ISAslots (FIG. 5G) whereas the control stations 22 ₁, 22 ₂ have two PCIslots 84, four ISA slots 86, and a floppy disk drive 60 (FIG. 5H). TheI/O adapter cards 85 may also include SCSI, ATM, Ethernet FDDI and ESCONcards, for example. The motherboard also has mounted to it a flashmemory, or ROM having stored therein the CPU 80 self-test program (andBIOS).

[0055] It is noted that the processing unit module 28 is configured toenable use of market available processing unit module motherboards andI/O adapter cards 85. Motherboards may range anywhere from five slotmachines to eight slot machines, for example. Here, the motherboard 67is an Intel PBP133ED70NC. As noted above, the data mover or controlstation processing unit module 28 has eight I/O adapter card slots 84,86 (i.e., 3 PCI, 4 ISA, and 1 mixed PCI/ISA). It also has 4 SIMM slots82 (FIG. 5E), uses a Triton Chipset, and is capable of 100 MB sustainedthroughput between processing unit 28 main memory 82 a and the PCI bus.When the motherboard 67 is configured in a data mover, the two leftmostslots 84 house single channel SCSI cards, for example, that interface tothe storage devices in the data storage system 12 (FIG. 1). Moving tothe right, the next two slots 84 are for connection to the network 14(FIG. 1) (i.e., combinations of 100base T Ethernet, FDDI, ATM or otheradapters); the following two slots 86 to the right of the networkconnectors are here reserved for expansion, and the two rightmost slots86 are 10baseT Ethernet bus for communications between the data moverand the control stations 22 ₁, 22 ₂.

[0056] Because these motherboards 67 and adapter boards 85 are availablein large quantities from a variety of sources, the data server 10 hasrelatively low cost and high performance. Further, with respect to theuse of standard I/O adapter cards, the data server 10 can rapidly deploynew network interfaces to the market. A fully loaded data server 10 has60 slots 84, 86 that can be configured with network and/or storage I/Oadapter cards 85. Each server motherboard 67 has four available fulllength PCI slots and each control station has two available full lengthPCI slots. An exemplary data server 10 is configured with four-portEthernet network adapters and single SCSI adapters would yield a systemwith one hundred and twenty network 12 connections and thirty datastorage system 14 connections.

[0057] The server interconnect printed board 68 provides the status,control and communication interfaces for the server 10. In effect, theserver interconnect printed circuit boards 68 serve as a bridge betweenthe motherboard 67 and the server 10 via the backplanes 30 ₁-30 ₄. Theserver interconnect printed board 68 performs the following functions:(1) It provides a point of load DC-to-DC conversion for the motherboard67; (2) It contains a control bus that allows the control stationprocessing unit module 28 to perform numerous environmental operationsto the data mover processing unit modules 28; (3) It collects theenvironmental status that is local to the data mover and/or controlstation processing unit module 28 and reports on exceptional conditions;(4) It contains an Enhanced Parallel Port (EPP) which allows themotherboard 67 to gather Vital Product Data (VPD) and otherconfiguration information, enables their battery backup functions,solicits on exceptional system conditions, signals the control stationvia the control bus, and accesses other system interfaces; (5) Itcontains a Legacy Parallel Port (LGP) that interfaces the controlstation to the COMM board (COMMBD) which contains otherinformation/control about the system's configuration and environment;(6) It has the pair of the redundant Ethernet XCVRs to provide the meansin which the communications Ethernet bus 24 is routed to otherserver/control stations; and, (7) It provides the physical path formodem access from the control station.

[0058] Referring to FIG. 5B, 5C and 5E, a Teradyne High Density Metric(HDM) connector 93 is mounted to the rear of server interconnect printedcircuit board 68. The rear of the HDM connector 93 projects outward froma slot 94 provided in the rear panel 98 of the processing unit module 28(FIGS. 5D and 5F); FIG. 5F showing processing unit module 28 with theinterconnect printed circuit board 68 removed. The upper portion 95 ofconnector 93 is adapted to receive the 48 volts provided by the AC/DCconverters 38 (FIGS. 6 and 8) on the 48 volt bus system. The middle andlower portions 97, 99 of the connector 93 (FIG. 5B) are adapted toreceive signals via the backplanes 30 ₁-30 ₄. Disposed between themiddle and lower portions 97, 99 of connector 93 is a hole 101. The rearpanel 98 of the processing unit module 28 (FIG. 5B) is provided with ahole 105, as shown, disposed below the connector 93. As will bedescribed below in connection with the server cabinet 18, thisarrangement is used in a three-step “blind mating” arrangement enablinghot replacement of the processing unit module 28 from a backplane 30₁-30 ₄ into which the processing unit module 28 plugs.

[0059] Referring again to FIGS. 5G and 5H, the front panel bezels 110 ofthe data mover 20, module 28 and control station 22, module 28 areshown, respectively. The front bezels 110 have a handle 111, as shown.On the front bezels 110 of each are several switches 79 and indicators77. More particularly, a service switch used only for manufacture, powerenable LED indicators to indicate that power is enabled within the datamover 20 ₁-20 ₁₄, or control station 22 ₁-22 ₂; a fault LED to indicatea failure in the control station or data mover module 28, a push buttonreset switch to perform a hard reset to CPU 80 mounted on themotherboard, and status LEDs. (The reset switch is a mechanical switchwhich restarts the CPU 80 to initiate a boot of the operating systemsoftware into the main memory 82 a. As will be described in connectionwith FIG. 16, a program is stored in the processing unit module 28 (aportion in the flash memory mounted to the motherboard 67, mentionedabove, and another portion on the Ethernet adapter cards plugged intothe motherboard 67) to automatically reset the CPU 80 until the CPU 80finds an operational and valid source for the operating systemsoftware.) Here, there are twelve small status LEDs 77 (FIGS. 5G, 5H) toprovide additional information about the internal state of the datamover and/or control station module. The front bezel 110 of the controlstation 22 module 28 shows the physical location of the I/O adapter cardslots 84, 86. As described above, slot numbers 3 and 4 are PCI slots andslots 5 through 8 are ISA slots. FIG. 5G shows the front bezel 110 ofthe data mover and the physical location of the I/O adapter card slots84, 86. As described above, slots 1 through 4 are PCI slots. Slotnumbers 5 through 8 are ISA slots. Also, the front bezel 110 is providedwith a pair of openings 113 a, 113 b (FIG. 7) to enable connection ofthe pair of redundant Ethernet I/O adapter cards via connectors 113 c,113 d (FIG. 7) between the pair of Ethernet I/O adapter cards (EI/O) anda corresponding one of a pair of redundant Ethernet transceivers (XCVRs)mounted to the server interconnect printed circuit boards 68, as shown,and to be described in connection with, FIG. 7.

[0060] Thus, in summary, the data movers/control stations comprise of amotherboard 67, a server interconnect printed circuit board 68, I/Oadapter cards 85, DC powered fan 76, 78, and a mechanical enclosure, orcase for the processing unit module 28. The case has a latchingmechanism 222 to be described in connection with FIGS. 10A-10F. Thus,referring again briefly to FIGS. 5G and 5H, the modules 28 include ontheir front bezels 110 panel, a handle 111 and locking mechanism 222that is used, as described above, to insert or remove the module 28 fromthe cabinet 18. The I/O adapter card slots 1-8 for data movers 20 ₁-20₁₄ and slots 3-8 for control stations 22 ₁, 22 ₂ are visible from thefront bezels 110 of the data mover or control station module 28.

I/O Adapter Card Mounting Plate 312

[0061] An exemplary array of I/O adapter cards 85 is shown in FIG. 9A.It is noted that the I/O cards 85 are off-the-shelf printed circuitboards having an L-shaped mounting bracket 301. Each one of the L-shapedmounting brackets 301 has a leg portion 304 fastened to a printedcircuit board, or card 302 and a foot portion 306 with a U-shapedopening 308 passing through the foot portion 306 normally used toreceive a screw, not shown, used to securing the bracket 301 to amounting member 310 of the case (i.e., module 28 enclosure), forexample. The L-shaped mounting bracket 301 is, noted above, affixed to aprinted circuit card 302. The printed circuit card 302 is adapted tohave its bottom edge 303 plug into one of the slot 84, 86 (FIG. 5E) inthe motherboard 67. After the printed circuit card 302 is plugged intothe motherboard 67, rather then securing the L-shaped mounting bracket301 to the front panel 110 mounting member 310 with individual screws, amounting plate 312 having a plurality of captive screws 314 (FIG. 9C) isused.

[0062] More particularly, and referring also to FIGS. 5B, 5F and 9B, themounting plate 312 has press fit into a plurality of holes 316 (FIG. 9C)formed therein a corresponding plurality of screw fixtures 320, heremanufactured by Penn Engineering and Manufacturing Company, Danboro, Pa.18916, and a plurality of press fit pins 317 having tips 317 a whichproject from the bottom of the plate 312 as a single unit to engage theU-shaped openings 308 in place of individual screws. The screw fixtures320 have an outer collar which is press-fit into the holes 316 in themounting plate 312 to thereby secure the screw fixtures 320 to themounting plate 312 as a single unit. The screws 314 are rotatablymounted within the screw fixtures 320. The distal ends 320 of the screws314, and, as described above, the tips 317 a of pins 317, projectoutwardly from the bottom of the mounting plate 312. After one, or more,of the printed circuit boards 85 are plugged into the motherboard 67,the bottom of the mounting plate 312 is set over the horizontal footportion 306 of the L-shaped mounting brackets 301, as shown in FIG. 9B.The technician, using his/her thumb and forefinger about the outerperiphery of the screws 314, turns the screws 314 within the fixture 320clockwise to screw the screws 314 into the corresponding, tapped andthreaded holes 340 provided in the front panel 110 mounting member 310thereby mounting the entire mounting plate 312 to the front panel 110mounting member 310. Thus, the mounting plate 312, when secured to thefront panel mounting member 310, fastens the L-shaped brackets 304 tosuch front panel mounting member 310. Conversely, to remove one or moreI/O adapter cards 85, the technician turns the screws 314counter-clockwise until the mounting plate 312 is released from thefront panel mounting member 310. The technician then lifts and removesthe mounting plate 312. Once the mounting plate 312 is removed, thetechnician unplugs the desired I/O adapter card or cards 85. As notedabove, the screws are captive to the mounting plate 312 (i.e, the screws314 in their fixtures 320 are captive hardware to the mounting plate312). Further, the mounting plate 312 is a relatively large piece.Therefore, instead of having to contend with six or eight individualscrews, which are relatively small, difficult to handle individually,and subject to being dropped and difficult to retrieve, the single,relatively large mounting plate with captive hardware greatlyfacilitates the insertion and/or removal of the I/O adapter cards 85.Still further, a screw driver is not required.

I/O Adapter Card Filler Plate

[0063] Referring now to FIGS. 9E-9F, an adapter card 85 filler plate 350is shown. The filler plate 350 has an L-shaped mounting bracket 301′with a foot portion 306. The foot portion 306 has an U-shaped opening308 similar to that for the I/O adapter card 302 mounting brackets 301,described above. Here, however, the leg portion 351 has a plurality ofholes 352 formed therethrough to provide a honey-combed structure. Ifone of the I/O adapter cards 302 is not needed, one of the adapted cardfiller plates 350 is substituted for it, as shown in FIGS. 9F and 9G,where the fifth and sixth from the left adapter card filler plates 350are used in the module 28 to replace a pair of unused I/O adapter cards302. The filler plates 350 are fastened to the case of the module withthe mounting plate 312 (FIG. 9C). Thus, in this example, the tips 317 aof pins 317 engage the U-shaped openings 308. This honey-combed, adaptedcard filler plate 350 improves air-flow through the front panel andacross the motherboard 67. It is noted that the distal end 353 isadapted to slip into slot S (FIG. 5D) provided in bottom panel of thecase of module 28.

Server 10 Backplanes 30 ₁-30 ₂ With Printed Circuit Ethernet Bus

[0064] Referring again to FIGS. 3C-3E, the relationship between theserver backplanes 30 ₁-30 ₄ and the data movers 20 ₁-20 ₁₄ processingunit modules 28 and control stations 22 ₁-22 ₂ processing unit modules28, is shown. Thus, four backplanes 30 ₁-30 ₄ connect up to fourteenstream servers 20 ₁-20 ₁₄ and two control stations 22 ₁-22 ₂. Moreparticularly, fastened within in the cabinet 18 (FIG. 1) is a set offour sheet metal chassis 200, an exemplary one thereof being shown inFIG. 11A. Disposed between upper and lower panels 202, 204 is anintermediate shelf 206 fastened to opposing side panels 210.Partitioning members 212 a, 212 b (FIG. 8B), are adapted for fasteningwith captive hardware screws 214, to threaded holes 207 provided in thefront and rear center of the lower panel 204 (i.e., which serves as abottom shelf) and the front and rear center of the shelf 206 (whichserves as a middle shelf) to divide the lower panel 204 and/or the shelf206 into right and left slots or compartments 213 a, 213 b eachcompartment being adapted to receive a module 28, as shown in FIG. 11F.Thus, when the partitioning members 212 a, 212 b are fastened to lowerpanel 204 and the shelf 206, the chassis 200 is adapted to receive fourmodules 28, as described above, as shown in FIG. 11F. If, however, thewidth of a module 28 case is increased in the future, the partitioningmembers 212 a, 212 b may be removed allowing insertion of a largermodule 28 case. The single module 28 case would have its serverinterconnect printed circuit board connector 93 (FIG. 5B) on the leftside of its case so that when the single module 28 case is slide ontothe shelf the connector 93 will be able to be plugged into (i.e., matewith) the backplane 30 ₁-30 ₄. It is noted that a screw 253 (FIG. 11G)is adapted to pass through holes 253 a in the backplane (FIGS. 12B, 13Aand 13B) and be threaded into a hole 253 d in the rear wall 253 c ofpartitioning member 212 b.

[0065] More particularly, and referring also to FIG. 11G, the back panel240 of the chassis 200 four slots 241 a, 241 b to enable the connectors93 of each of the four modules 28 to project therefrom. If a singlemodule 28 is used on any one of the two shelves 204, 206, the connector93 of such module 28 will project from the appropriate one of the slots241 a.

[0066] The front of the side panels 210 are provided with slots 218, asshown in FIG. 11A, 11D. As will be described, such slots 218 are adaptedto engage the locking mechanism 222 (FIGS. 5G and 5H) on the module 28to lock/unlock the module 28 in the cabinet 18.

[0067] As mentioned above, the chassis 220 has a rear panel 240 fastento it, here welded, as shown in FIG. 11G. The rear panel 240 is providedwith nine posts 242 (FIG. 11E) to receive corresponding nine holes 248passing though a corresponding one of the four backplanes 30 ₁-30 ₄, anexemplary one being shown in FIG. 12A and 12B, the chassis 200 not beingshown for clarity. Further, the rear panel 240 carries captive screws243 which are adapted to pass through holes 253 a in the backplane (FIG.13A, 13B) into a threaded rear wall 235 c (FIG. 11C) in partitioningmember 212 b (FIG. 11C).

[0068] The backplanes 30 ₁-30 ₄ are identical in construction, anexemplary one thereof, here backplane 30 ₁ being shown in FIGS. 12A and12B. The backplane 30 ₁ is a multi-level printed circuit board. Thefront of the backplane 30 ₁ is shown in FIG. 12A to include four ovalapertures 250 a-250 d (FIG. 11A) adapted to align with the four ovalopenings 252 a-252 d provided in the chassis 200 rear panel 240 (FIG.11E). Four Teradyne HDM connectors 254 a-254 d (FIGS. 12A, 12B) arefastened to the backplane 30 ₁, as shown; one to the right of acorresponding one of the four apertures 250 a-250 d in FIG. 12B lookingfrom the front of the cabinet 18. Each Teradyne HDM connector 254 a-254d includes a forward projecting alignment pin 260, as shown forexemplary connector 254 a in FIGS. 12C and 12D. Each backplane 30 ₁-30 ₄has fastened to it four longer alignment pins 261, as shown more clearlyin FIGS. 12C and 12D.

[0069] As described above in connection with FIG. 5B, a Teradyne HighDensity Metric (HDM) connector 93 is mounted to the rear serverinterconnect printed circuit board 68 (FIG. 12D). More particularly, theserver interconnect printed circuit board 68 is loosely mounted to thecase 28 so that it may move slightly upward if needed in matingconnector 93 with connector 254 a. The rear of the HDM connector 33projects outward from a slot 94 provided in the rear of the module 28(FIG. 5F) and in the rear panel 242 of chassis 200 (FIG. 11E); FIG. 5Fshowing module 28 with the interconnect printed circuit board 68removed. The upper portion 95 of connector 93 is adapted to receive the48 volts provided by the AC/DC supplies 38 (FIG. 6). The mid and lowerportions 97, 94 of the connector 93 are adapted to receive signals.Disposed between the mid and lower portions 97, 94 of connector 93 is ahole 41, as described above in connection with FIG. 5B. The rear panel98 of the module 28 (FIG. 5B) is provided with a hole 105, as shown,disposed below the connector 93. The HDM connectors 93 of the datamovers 20 ₁-20 ₄ plug into backplane 30 ₁; the HDM connectors 93 of datamovers 20 ₅-20 ₈ plug into backplane 30 ₂; the HDM connectors 93 of datamovers 20 ₉-20 ₁₂ plug into backplane 30 ₃; and the HDM connectors 93 ofdata movers 20 ₁₃, 20 ₁₄ and of control stations 22 ₁, 22 ₂ plug intobackplanes 30 ₄. The control stations 22 ₁, 22 ₂ modules 28 as well asthe data movers 20 ₁-20 ₁₄ modules 28 are hot replaceable directly(i.e., without any cables between the module 28 and the backplane 30₁-30 ₄ and without any interruption to the operation and data processingof the server 10).

[0070] In operation, the plugging of a module 28 into the backplane 30₁, for example, is a three-step process. First, as the module 28 is slidbackwards toward the backplane 30 ₁, the point at the end of pin 261engages the hole 105 (FIG. 12A) in the module 28 thereby guiding (i.e.,aligning) the module 28 onto the shaft of the pin 261. Next, during thesecond step, as the chassis 28 is further urged rearward, the tip ofshorter pin 260 of HDM connector 254 a engages the hole 101 in HDMconnector 93 thereby guiding the connector 93 onto the shaft of the pin260. As noted above, the server interconnect printed circuit board 68 isloosely mounted to the module 28 so that it may move slightly in themodule 28 as hole 101 and pin 260 engage each other. Finally, during thethird step, the plastic housings 257, 259 of the HDM connectors 93, 254a engage each other. This procedure enables “blind-mating” between themodule 28 (i.e., the sheet metal case of the module 28) and thebackplane 30, thereby enabling the module 28 to be hot plugged into, orremoved from the backplane 30 ₁, and hence into the data server 10 (FIG.1). It is noted that the module 28 is plugged into DC provided by thepower supplies 38 (FIG. 6), as distinguished from AC. That is, theprocessing unit module 28 has its own CPU 50, I/O adapter cards 85, mainmemory 82 a and the DC/DC converter 70, is being hot plugged into, orremoved from a here 48 volt DC source; i.e., a 48 volt battery backed DCsupply 38.

[0071] Once the HDM connectors 93, 254 a are plugged into each other,the module 28 is locked into the cabinet 18. More particularly, asdescribed above, the bottom of each module 28 has pivotally mounted tothe front, lower left corner thereof a locking mechanism 222, as shownmore clearly in FIGS. 5D and 10A-10F.

[0072] Here, the locking mechanism 222 is an arm 223 pivotally mountedat point 224 (FIG. 10C) to the bottom of the module 28. It is noted thatthe left side 226 of the locking mechanism arm 223 projects beyond theside 228 of module 28, as shown when the right side 229 of the arm 223is manually urged rearward against the chassis 28; i.e., in the positionshown in FIGS. 10A-10C.

[0073] In order to insert the module 28 into the chassis 200, thetechnician rotates the right side 229 of the arm 223 (i.e., the handle)forward, i.e., in the direction of arrow 231 (FIG. 10C), so that theleft side 226 of the arm 223 rotates rearward into a slot 230 providedin the left side 226 of the module 28, as shown in FIGS. 10D-10F. Insuch position, the left side 226 of arm 223 no longer projects beyondthe left side 228 of the module 28 (FIG. 10F), but rather swingsrearward and becomes recessed in the slot 230 provided in the left side226 of the module 28. In this position, the module 28 is slid onto thelower panel, or shelf, as the case may be, of the chassis 200 (FIG.11D). When fully inserted, the technician urges the right side 229 ofthe arm 223 forward causing the left side 226 of the arm 223 to pivotrearward (i.e., in the reverse direction of arrow 23) into the slot 218(FIG. 11C, 11D) provided in the side 206 of the chassis thereby lockingthe module 220 in the chassis, i.e., preventing its removal unless thetechnician decides to remove the module 28 by again urging the rightside 229 of the arm 223 forward, as described above. It is noted thatscrew 225 (FIG. 10A) in arm 223 screws into hole 225 a (FIG. 10D).

Backplane Having Strip Transmission Line Ethernet

[0074] The backplanes 30 ₁-30 ₄ are multi-layer printed circuit boards.Patterned into the front and back surfaces of one of the dielectriclayers (referred to collectively herein as a dielectric substrate) ofthe printed circuit boards of the backplane 30 ₁-30 ₄ are stripconductor circuitry 262F, 262B, as shown in FIGS. 12A and 12B,respectively. Patterned into the front and back surfaces of another oneof the printed circuit board layer of the backplane 30 ₁-30 ₄ are stripconductor circuitry, not shown for a redundant Ethernet bus. The twolayers are bonded together with suitable dielectric insulation toprevent electrical short circuits developing between the redundantEthernet busses 24. Considering one of the two Ethernet buses, here bus24 a, and recognizing that the second bus 24 b (FIG. 8) is substantiallyidentical to the first Ethernet bus 24 a, the strip conductor circuitry262F, 282B meanders, as shown, from a first Ethernet connector 270 a,serially to a pair of pins 274, 276 of each of the Teradyne connectors254 a-254 d to a second Ethernet connector 270 b thereby providing thelocal Ethernet bus 24 a (FIG. 1) interconnecting the four modules 28plugged into the backplane 30 ₁. (It is noted that Ethernet connectors270′a, 270′b are used for the redundant bus 24 b, not shown).

[0075] Here, four Ethernet connectors 270 a, 270 b, 270 ′a-270′d, arehere BNC 10Base2 Ethernet connectors, mounted adjacent to acorresponding one of the apertures 250 a-250 d. Each Ethernet connector270 a-270 b is a coaxial connector having a center conductor 280 (FIG.12A) and an outer conductor 282 (FIG. 11B). The center conductors 280 ofthe four Ethernet coaxial connectors 270 a, 270 b are connected to stripconductor circuitry 262F while the outer conductor 282 is connected tostrip conductor circuitry 262R. It is noted that the strip conductors262F, 262R overlay one another as they pass from the first Ethernetconnector 270 a to the second Ethernet connector 270 b. Further, thewidth of the return strip conductor 262R is wider that the width of thesignal strip conductor 262F thereby providing a strip transmission line.In order to emulate a coaxial transmission line, the AC impedance and DCresistance of the overlaying strip conductor (i.e., the striptransmission line) are designed to have the substantially the same ACimpedance and DC resistance of an Ethernet coaxial transmission line.More particularly, the AC impedance and DC resistance of the overlayingstrip conductor (i.e., the strip transmission line) is designed toprovide an AC impedance, Z, of 50 ohms and a DC resistance, R, of 1.37milli-ohms per inch. The following equations may be used:$Z = {\frac{87}{( {e_{\tau} + 1.41} )^{1/2}}\ln \quad \frac{5.98\quad h}{( {{{.8}w} + t} )}}$R = ρ  (L/A)  Ω  /inch

[0076] where:

[0077] e_(r) is the permissivity of the dielectric layer

[0078] w is the width of the signal strip conductor 262F

[0079] h is the thickness of the dielectric layer

[0080] t is the thickness of the signal conductor 262F

[0081] ρ is the resistivity of the signal or return conductor 262F, 262R

[0082] L is the length of the signal conductor 262F and

[0083] A is the area of the signal conductor 262F

[0084] By altering the geometry of the height (h), width (w), thickness(t), length (L) and area (A) the values of Z=50 ohms and R=1.37milli-ohms per inch are obtained. It should be noted that the returnconductor 262R serves as an radio frequency ground plane for the signalconductor 262F and therefore should be wider that the signal conductor262F. That is, the signal on the Ethernet bus 24 a, 24 b has a frequencyof 10 MHz. Thus, the overlaying signal conductor 262F and returnconductor 262F (with the intermediate dielectric printed circuit boardlayer) provide a strip transmission line for the Ethernet 10 MHz signal.Thus, the return conductor 262R effectively serves an a non-DC ground,RF ground plane for the strip transmission line and is here 5 timesgreater in width than the width, w, of the signal conductor.

[0085] To put it another way, the Ethernet busses 24 a, 24 b on thebackplane 30, are formed as strip transmission lines. That is, thebackplane printed circuit board is provided with a pair of overlyingstrip conductors forming a strip transmission line. The striptransmission line is configured to have electrical characteristics of acoaxial transmission line. More particularly, the AC impedance and DCresistance of the strip transmission line are selected to configure thestrip transmission line as an Ethernet coaxial transmission line.

[0086] Referring now to FIG. 7, the interconnection among the modules 28via the Ethernet buses 24 a is shown. It is noted that while there are apair of Ethernet busses 24 a, 24 b provided for redundancy, only one ofthe pair of busses, here bus 24 a is shown in detail. Thus, there arefour modules 28 shown for each one of the four chassis 200. Each module28 includes a pair of Ethernet I/O adapter card (EI/O) which is can beplugged into the motherboard 67 and which is in one of the slots 84, 86,as described above in connection with FIG. 5E. Each module 28 alsoincludes a server interconnect printed circuit board 68, as describedabove. The server interconnect printed circuit board 68 have a pair ofredundant Ethernet transceivers (XCVRs) mounted to it and has a TeradyneHDM connector 93 adapted for plugging into a mating Teradyne HDMconnector 254 a-254 d mounted to the backplane 30 ₁-30 ₄.

[0087] The strip conductors 262F, 262R are connected to pins 272, 274 ofthe HDM connectors 254 a-254 d, as shown and as described above inconnection with FIGS. 12A, 12B. The pins 272, 274 electrically connectto the corresponding mating pin of the Teradyne connector 93 mounted tothe server interconnect printed circuit board 68. In this way, themodules 28 are internally interconnected through the Ethernet bus 24 a(or the redundant Ethernet bus 24 b). That is, the strip transmissionline passes from one processing unit module 28 to another module 28 in adaisy-chain, or serial manner connecting the four modules 28 pluggedinto each one of the backplanes 30 ₁-30 ₄. The distance between eachpair of directly connected Ethernet XCVRs must be greater than 20 inchestherefore, the strip transmission line meanders about the backplane asshown in FIG. 12A, 12B. It is noted that one of the coaxial connectors,here connector 270 a of backplane 30 ₁ is terminated in a matchingimpedance, here a 50 ohm resistor 290. The other one of the coaxialconnectors 270 b of backplane 30 ₁ is coupled to the coaxial connector270 a of the next backplane 30 ₂ by a coaxial connector 292 and coaxialjumper cable, as indicated. It is to be noted that this coaxialconnector 270 b is not terminated in a matched 50 resistor. The processrepeats until the last coaxial connector 270 b of backplane 30 ₄ isterminated in a matched impedance, here 50 ohm resistor, as shown,thereby serially connecting the 14 data servers 20 ₁-20 ₁₄ and twocontrol stations 22 ₁, 22 ₂, as shown.

Cable Management System

[0088] “Front-end” (i.e. network 14, FIG. 1) and “back-end” (i.e.,storage system 12) cables attached to the I/O adapter cards in slots 1-8or 3-8, as the case may be, via the front of the data mover or controlstation module enclosure 28. The cabling is achieved through a cablemanagement system. More particularly, cabling is achieved through front,side positioned cable channels 300, shown in FIG. 3B and to be describedin connection with FIGS. 14A-14C. The frame of the cabinet 18, shown inFIG. 14A, has provided in the left and right front regions thereof cablechannels 300. Each channel 300 includes one of four vertical edge struts302 at each of the four corners of the cabinet 18, as shown, and anadditional vertically extending strut 304. Connected to bridge theadditional struts 304 and the corner strut 302 are vertically spacedstraps 308, as shown. Each of the straps 308 has mating Velcrofasteners, not shown, at ends thereof. The rear portion of each strap308 is looped through slots formed in the channel 300 to secure thestrap 308 to the channel. When unfastened, the cables, such as cables310, are manually held against the rear wall 312 of the channel 300 andthen the cables 310 are secured in the channel 300 by manually fasteningthe ends of the straps 308 together, as shown. Such arrangement providesstructure for neatly routing the cables 310 through the cabinet 18 atonly the added cost of the fasteners since the frame is required anyway.

Power Management System 40 With Redundant, External, Hot ReplaceableBattery Chargers

[0089] The power management system 40 is shown schematically in FIG. 6.The system includes dual (i.e., redundant) AC power lines 37 a, 37 bfeeding the Emergency Power Off (EPO) box 37. The EPO 37 is electricallyconnected to the L-shaped printed circuit board connector 44. TheL-shaped printed circuit board 44 is electrically connected to thebackplanes 30 ₁-30 ₄. Also electrically connected to the L-shapedprinted circuit board 44 are the pair of redundant, independently, hotreplaceable battery chargers 48 a, 48 b and six AC/DC converters 38. TheAC/DC converters 38 are fed AC power from the AC lines 37 a, 37 bthrough the EPO 42. The L-shaped printed circuit board 44 distributes DCto the pair of battery chargers 48 a, 48 b and DC, here 48 volts to themodule 28 (i.e., the server interconnect printed circuit boards 68), viathe backplanes 30 ₁-30 ₄, as discussed above.

[0090] It is noted that while provision has been made to provide aFaraday cage that houses six AC-to-DC converters 38 to thereby provide a5 plus 1 redundant power supply configuration.

[0091] The system can still operate in the event of a failure of one ofthe AC-DC converters 38. The total number of AC-to-DC converters withthe server 10 is six. Here, in FIG. 6 only four are shown; two are usedfor expansion purposes and four are used for a fully configured system.A minimum redundant configuration would be 1+1 AC-to-DC converters 38and a maximum redundant configuration would be 3+1 AC-to-DC converters38. The control stations 20 can detect the presence of all of the systemcomponents (e.g., processing unit modules 28, Ac-Dc converters 38,COMMBDs, etc.) and can algorithmically determine if there are enoughAC-DC converters 38 to power the server 10 before power is actuallyapplied to any of the other system modules 28.

[0092] A mechanical enclosure provides a Faraday cage for EMI emissions.Empty I/O adapter card slots require small filler panels to prevent theleakage EMI. The mechanical case of the module 28 also provides ESDprotection to the internal printed circuit boards, SIMMs and disk drive(i.e., the control stations 22 have internal floppy and hard diskdrives). Each COMMBD 54, as noted above, is adapted to sense a varietyof conditions, including: which data movers are present in each datamover backplane; which backplanes are present; whether there areterminators on the backplane; how many battery chargers there are andwhether the cables are plugged in; EPO presence or absence; the numberof power supplies (i.e., one to six); mux board 53 presence or absence;CDROM presence or absence. The L-shaped printed circuit board 44 is, asnoted above, the wiring backbone of the system. There are two facets tothe L-shaped printed circuit board 44, as noted above: there areconnections on the L-shaped printed circuit board 44 itself; and, thereis a connector plate, not shown, behind the L-shaped printed circuitboard 44 for plugging in the EPO box 42 and chargers 38 allowing for“quick-disconnect” of the batteries 47 and chargers 48 a, 48 b. Theconnector plate has mating connectors that mate to the EPO 42 andchargers 38. There are also ribbon cables 31, as noted above, that comeout of the L-shaped printed circuit board 44 to electrically connect tothe backplanes 30 ₁-30 ₄. Logically, then, the L-shaped printed circuitboard 44 connects to the EPO box 37 and the chargers 48 a, 48 b, but itdoes so through a series of cables having other ends fixed to themodules 28 (and routed through the channels 300) so that the modules 28can be removed.

Operating System Software Boot Program Execution Method

[0093] Referring now to FIG. 15, the server 10 of FIG. 2 is shownconnected to a test network 100 via the Ethernet during factory test.Referring also to FIG. 16, a flow diagram of a method for booting anoperating system software into the main memory 82 a of each of theprocessing unit modules 28 used in data movers 22 and control stations24 of the data server 10 of FIG. 2 during either factory test, as inFIG. 15 or during normal operation, as in FIG. 1. It is noted that theintegrated cached disk array storage system 12 (FIG. 1) includes valid(e.g., valid format) operating system software, here DOS, which could bebooted into the main memory 82 a of a processing unit module 28 of theserver 10. However, during normal operation (i.e., after delivery of thesystem to a customer), if there has been a power failure, the time tothe have the storage system 12 operating system software available(i.e., valid) for use by the processing unit module 28 after power isrestored is much greater than the time the processing unit module 28 CPU80 is ready to boot such operating system software into its main memory82 a. Thus, in order to prevent the CPU 80 from getting locked into anon-bootable condition because of the unavailability of the storagesystem 12 operating system software, the method shown in FIG. 16 is usedto sequentially restart the CPU 80 in its search for operational andvalid operating system software.

[0094] In a factory environment, the server 10 may be tested withoutbeing connected to either the storage system 12 (FIG. 1) or the network14 (another possible source of an operational and valid operating systemsoftware), as shown in FIG. 15. There, the server 10 processing unitmodules 28 are booted with an operating system software stored in thetest network 100.

[0095] The method may be summarized as follows: A program stored isstored in each one of the processing unit modules 28. The program isexecuted in parallel in each of the processing unit modules 28. Moreparticularly, a read only memory on the motherboard 67 of each module28, here a flash memory stores the CPU 80 self-test portion of theprogram and the remaining portion is stored on the Ethernet I/O adaptercard in the processing unit module 28. The program is executed tosequentially search a plurality of possible sources of the operatingsystem software during a boot-up phase. The possible sources of theoperating system software are: floppy drive, local hard drive (i.e., ahard drive of the processing unit module 28), CD ROM drive, a drive onthe network 14 (FIG. 1), a hard drive of the storage system 12 (FIG. 1),a tape drive, for example. When a possible source of the operatingsystem software is detected, the CPU 80 checks to determine whether suchdetected source is operational and has a valid boot format. If thedetected source is operational and has a valid boot format, the CPU 80boots the detected operating system software source into the main memory82 a. If the detected source is either non-operational or does not havea valid boot format (i.e., the source is operational but the CPU 80reports “non-system disk error”, for example), the CPU 80 checks theanother one of the possible operating system software sources. If allsources are checked and none are either operational nor have a validboot format, the CPU 80 repeats the aforementioned sequentially searchof the possible operating system software sources.

[0096] Referring to FIG. 16, the power to the CPU 80 in the processingunit module 28 is turned on (Step 400). The CPU 80 then starts itsself-test by executing a program stored in the flash memory ROM in theprocessing unit module 28 to search for an operational, valid softwareoperating system software Step 401). Here, in this example, CPU 80, inresponse to the executable program stored in the ROM of the processingunit module 28, sequentially searches a plurality of possible sources ofthe operating system software during a boot-up phase. More particularly,here the CPU 80 in this example, first searches the floppy drive for anoperational and valid operating system software, for example DOSoperating system software (Step 402). If, in Step 403, the CPU 80detects that the floppy drive has an operational and valid operatingsystem software, the CPU 80 boots such operating system software intothe main memory 82 a (Step 404); if either an operational system is notdetected by the CPU 80 on the floppy or is found by the CPU 80 not to bea valid operating system software, the CPU 80 searches another one ofthe possible sources, here the local hard drive (Step 405). If, in Step406, the CPU 80 detects that the local hard drive has an operational andvalid operating system software (for example, the local hard drive hasoperational and valid operating system software, the CPU 80 boots suchoperating system software into the main memory 82 a (Step 407); ifeither an operational system is not detected by the CPU 80 on the localhard drive or if detected is found not by the CPU 80 to be a validoperating system software, the CPU 80 searches another one of thepossible sources, here the storage system 12 Step 408). If, in Step 409,the CPU 80 detects that the storage system 12 has an operational andvalid operating system software, the CPU 80 boots such operating systemsoftware into the main memory 82 a (Step 410); if either an operationalsystem is not detected by the CPU 80 on the storage system 12 or ifdetected is found not by the CPU 80 to be a valid operating systemsoftware, the CPU 80 searches another one of the possible sources, herethe test network 100 (FIG. 15) (Step 409). If, in Step 411, the testnetwork 100 is used, as in a factory test, the system will boot;however, if the test network 100 is not used, as when the server 12 isat a customer, the program will reset the CPU (Step 414) and returns toStep 401 to again sequentially search for an operational and validoperating system software.

[0097] Other embodiments of the invention are within the spirit andscope of the appended claims. For example, the redundant, independentlyreplaceable battery chargers may be used in the memory system 12 tocharge a battery in such system 12.

[0098] What is claimed is:

1. A data server having a plurality of hot replaceable processing units,each one of the processing units including a central processing unit anda main memory.
 2. The data server recited in claim 1 wherein each one ofthe processing units includes a DC to DC converter.
 3. A data server,comprising: a backplane having a first electrical connector; a pluralityof DC powered processing unit modules each one having: a motherboard; acentral processing unit plugged into the motherboard; a main memoryplugged into the motherboard; and an interconnect printed circuit board,electrically connected to the motherboard, the interconnect printedcircuit board having a second electrical connector adapted to mate with,and electrically connect to, the first electrical connector.
 4. A dataserver, comprising: a backplane having a first electrical connector; aprocessing unit module, having: motherboard having plugged therein: acentral processing unit; and, a main memory; an interconnect printedcircuit board, electrically connected to the motherboard, suchinterconnect printed circuit board having a second electrical connector;and wherein such first and second electrical connectors are adapted toenable the processing unit module to be hot plugged into, or removedfrom, the backplane.
 5. The data server recited in claim 4 wherein eachone of the interconnect printed circuit boards has mounted thereon a DCto DC converter electrically connected to the backplane.
 6. A dataserver, comprising: a cabinet having a plurality of slots therein; abackplane section disposed at a rear of the slots; a plurality of hotreplaceable, DC powered, processing unit modules, each one being adaptedto be inserted in, or removed from, a corresponding one of the slots assuch one of the processing unit modules is plugged into, or unpluggedfrom the backplane.
 7. The data server recited in claim 6 wherein eachone of the backplanes has a first electrical connector and wherein eachone of the processing unit modules includes: a case, such case havingstored therein: a motherboard; a central processing unit plugged intothe motherboard; and, a main memory plugged into the motherboard; aninterconnect printed circuit board, electrically connected to themotherboard, such interconnect printed circuit board having a secondelectrical connector at a rear end of the interconnect printed circuitboard; and wherein such second electrical connector is adapted enablethe processing unit module to plug into the first electrical connector.8. The data server recited in claim 7 wherein the interconnect printedcircuit board has mounted thereto a DC to DC converter, such DC to DCconverter being electrically connected to the second electricalconnector, and wherein the first electrical connector is coupled to a DCsupply voltage.
 9. The data server recited in claim 8 wherein the DC toDC converter supplies DC power to the processing unit.
 10. The dataserver recited in claim 9 wherein each one of the cases includes a fanand wherein the DC to DC converter supplies DC power to the fan.
 11. Adata server, comprising: a plurality of hot replaceable processing unitmodules, each one of the processing unit modules including: amotherboard having plugged therein: a CPU, main memory and I/O adaptedcard; an interconnect printed board, such interconnect printed circuitboard having a first electrical connector and a DC to DC converterelectrically connected to the first electrical connector; and abackplane having a second electrical connector adapted to mate with, andelectrically connect to, the first electrical connector for coupling toa DC power supply.